The present invention relates generally to the ink jet printing art, and in particular, to a hand-held marking device which utilizes an ink jet print-head in order to selectively apply ink to a print medium. Preferably, the print-head is part of a replaceable cartridge that may be replaced as desired.
Various ink jet technologies that are utilized in conjunction with printer devices are known in the art. These generally include continuous feed ink jet systems and drop-on-demand systems. One such printer that is based on a drop-on-demand system utilizes a print-head that is disposed on a carriage. The carriage is translatable over a print medium. Relatively sophisticated electronics are employed including timing and encoding circuitry to move the print medium in a first direction and to move the carriage in an orthogonal direction thereto.
The print-head in these systems typically comprises a piezoelectric transducer, an ink chamber, and an ejection nozzle. The transducer is disposed to selectively vibrate the ink chamber in proximate relation to the ejection nozzle. In operation, a non-pressurized ink pulse jet is generated at a desired frequency, i.e., 1 to 10 kHz. The ink drops are generated on demand by a transient pressure pulse and directed toward a receiving surface. Volume changes in the ink chamber located behind the ink ejection nozzle cause the droplets to eject. These volume changes are generated by the piezoelectric transducer.
The impulse jets are relatively compact in design. Accordingly, print-heads based on this technology typically have arrays which include tens of nozzles operating synchronously.
Another technology which is known is the xe2x80x9cbubble jetxe2x80x9d or thermal jet printing technology. In these types of printers, a supply channel is provided which leads from an ink reservoir to one or a plurality of nozzles on an orifice plate. This supply channel is designed to provide a certain amount of resistance to flow. A thermo-electric transducer disposed proximate to the supply channel heats up the ink and produces a small vapor bubble. The vapor bubble drives the ink from the nozzle with a certain force. The maximum ejection frequency is approximately 4 kHz.
While these systems perform satisfactorily in printing capacities for which they are intended, it would be desirable to have a hand-held marking device based on these technologies.
Accordingly, it is an object of the invention to provide a hand-held marker that utilizes an ink jet technology.
It is a further object of the invention to provide an ink jet marker that is relatively simple in design and construction.
It is a further object of the invention to provide an ink jet marker that includes a replaceable cartridge that may be readily installed or removed from a marker body.
The present invention provides these and other additional objects and advantages in an ink jet marking device. The marking device comprises an elongated body having a generally cylindrical or other desired shape and adapted for use as a writing instrument. A replaceable cartridge containing a reservoir of ink is disposed within the body, preferably at one end of the device body. The marking device also comprises an ink jet print-head disposed at the opposite end of the instrument body, and in fluid communication with the reservoir. The print-head includes a plurality of ejection nozzles adapted to dispense a selected amount of ink upon receipt of control signals by the print-head. The marking device also comprises an electrical control circuit coupled to the ink jet print-head disposed to provide the control signals to the ink jet print-head.
In one embodiment, the electrical control circuit is located in a base station console. The electrical circuit is connected to the print-head with electrical terminals. Alternatively, the electrical control circuit is disposed within the cylindrical body of the marking device.
In another aspect of the invention, a replaceable ink cartridge is provided for insertion within a hand-held writing instrument body. The cartridge includes a reservoir of ink adapted for placement within the body and optionally a print-head. The print-head includes a plurality of ejection nozzles coupled with the reservoir. The print-head is adapted to dispense selected amounts of ink from the plurality of ejection nozzles upon receipt of control signals provided by an electrical circuit. In one embodiment, a thin film battery is wrapped around the reservoir body.